Koga Kuchiki is the secondary antagonist of the Zanpaktou Rebellion arc in the anime series Bleach. He is the former 3rd seat of Squad 6 of the Gotei 13, the son-in-law of Ginrei Kuchiki and the uncle of Byakuya Kuchiki. After he was betrayed by allied officers, Koga became convinced that they were jealous of his power, which signalled his descent into madness, eventually resulting in him getting sealed away. The arc revolves largely around his Zanpaktou Muramasa and his attempt to free Koga from his prison.
He is voiced by Isshin Chiba in the Japanese version and David Vincent in the English version.
- Although Muramasa is the main antagonist overall, Koga can be considered the greater scope villain, as his betrayal of Muramasa is what triggers all the events after his death.